SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '15041df895e5054e2a53509c6a988f67369b05cd4ade8cebb761821b1b8bf62b' 
  AND token = 'QEBCkv5/ukVBWzp1/X8KRYGvjvsrmIRUYeQI1SpyZn4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}